You might want to check with Canada Customs first, before you even try to make a deal on a tractor. Mr.s Trump and Trudeau had a pissing contest and I think us little guys got the shaft. In other words, I think the rules have changed thanks to that pissing contest.
Assembled in USA isn't the same as Made in USA. You will still need to pay the taxes and maybe duty, too. A customs broker is a bonus and maybe you can get clarification from them about the costs of importing.
If you go to CC, then try to get a hold of the top dog at that branch, he/she will be right up on the rules.